Improve D-Bus projection macros

* Use full path for std::collections::HashMap
* Avoid clash with macro use by suffixing internal vars with __
* Add DBusArg implementation for bool

Bug: 186492781
Tag: #floss
Test: manual - build floss on Linux

Change-Id: Icf097a581c0f30b27ea53fd20f5c6dfa1b2099a7